The factors influencing clinical outcomes after leukapheresis in acute leukaemia.

Leukapheresis is used for the mechanical removal of leukaemic cells in hyperleukocytosis. However, the effectiveness of leukapheresis remains unclear due to selection and confounding factors in the cohorts. We compared the effectiveness of leukapheresis among the subgroups according to either the 2016 World Health Organization classification or the number of cytogenetic abnormalities with a retrospective, single-centre study from January 2009 to December 2018. Acute myeloid leukaemia (AML, n = 212) and acute lymphoblastic leukaemia (ALL, n = 97) were included. The 30-day survival rates (95% confidence interval, 95% CI) for AML and ALL were 86.3% (81.6-90.9%) and 94.8% (90.3-99.2%), respectively. For AML, 'primary AML with myelodysplasia-related changes' and 'AML with biallelic mutation of CEBPA' showed better 30-day survival outcomes (P = 0.026) than the other subgroups. A higher platelet count after leukapheresis was associated with better 30-day survival in AML patients (P = 0.029). A decrease in blast percentage count after leukapheresis was associated with better 30-day survival in ALL patients (P = 0.034). Our study suggested that prophylactic platelet transfusion to raise the platelet count to 50 × 109/L or greater might improve clinical outcome in AML patients undergoing leukapheresis.

Automated Good Manufacturing Practice-compliant generation of human monocyte-derived dendritic cells from a complete apheresis product using a hollow-fiber bioreactor system overcomes a major hurdle in the manufacture of dendritic cells for cancer vaccines.

BACKGROUND: Although dendritic cell (DC)-based cancer vaccines represent a promising treatment strategy, its exploration in the clinic is hampered due to the need for Good Manufacturing Practice (GMP) facilities and associated trained staff for the generation of large numbers of DCs. The Quantum bioreactor system offered by Terumo BCT represents a hollow-fiber platform integrating GMP-compliant manufacturing steps in a closed system for automated cultivation of cellular products. In the respective established protocols, the hollow fibers are coated with fibronectin and trypsin is used to harvest the final cell product, which in the case of DCs allows processing of only one tenth of an apheresis product. MATERIALS AND RESULTS: We successfully developed a new protocol that circumvents the need for fibronectin coating and trypsin digestion, and makes the Quantum bioreactor system now suitable for generating large numbers of mature human monocyte-derived DCs (Mo-DCs) by processing a complete apheresis product at once. To achieve that, it needed a step-by-step optimization of DC-differentiation, e.g., the varying of media exchange rates and cytokine concentration until the total yield (% of input CD14+ monocytes), as well as the phenotype and functionality of mature Mo-DCs, became equivalent to those generated by our established standard production of Mo-DCs in cell culture bags. CONCLUSIONS: By using this new protocol for the Food and Drug Administration-approved Quantum system, it is now possible for the first time to process one complete apheresis to automatically generate large numbers of human Mo-DCs, making it much more feasible to exploit the potential of individualized DC-based immunotherapy.

Leukocytapheresis in nonmobilized donors for cellular therapy protocols: Evaluation of factors affecting collection efficiency of cells.

INTRODUCTION: Collection efficiency (CE1) of cells refers to the number of cells that are collected from the total number of cells processed by the apheresis device. Limited data are available about the CE1 of cells when performing leukocytapheresis in nonmobilized donors for cellular therapy purposes. The aim of our study was to evaluate donor- and procedure-related characteristics that might influence the CE1 of cells. MATERIAL AND METHODS: Variables that predicted the CE1 of cells were analyzed by longitudinal linear regression in a series of 1071 leukocytapheresis procedures on 249 nonmobilized donors. Donor-related characteristics considered were gender, age, total blood volume, and complete blood count (CBC) data. Procedure-related characteristics considered were vascular access and device used. RESULTS: Older donor age was associated with a decrease in the CE1 of leukocytes, lymphocytes, monocytes, and mononuclear cells (MNCs; sum of leukocytes and monocytes) and with an increase in the CE1 of platelets (P < .05). Preprocedure CBC data (leukocytes, lymphocytes, monocytes, and platelets) were associated with either a statistically significant increase or decrease in the CE1 of cells. Central line used as vascular access was associated with a statistically significant decrease in the CE1 of MNCs (P = .02). CONCLUSION: Donor's age, preprocedure CBC data as well as central line used as vascular access were factors associated with CE1 of cells. Knowing these characteristics is helpful in the apheresis unit when designing cellular therapy protocols in order to maximize the CE1 of the desired cell and to personalize collection variables for each donor.

Mononuclear cell collection for extracorporeal photopheresis by using the "off-line" system: A comparative study between COBE Spectra and Spectra Optia devices.

BACKGROUND: Extracorporeal photopheresis (ECP) is an efficient and established therapy to treat acute and chronic graft vs host disease (GVHD). Using an "off-line" method, the first step (mononuclear cell [MNC] collection) is decisive, as long as a high MNC yield and purity in the collected product is desirable. Two "off-line" devices were compared: the COBE Spectra and the Spectra Optia (Terumo BCT), using both continuous and intermittent protocols. PATIENTS AND METHODS: Twelve patients with GvHD (7 acute/5 chronic) were enrolled between June 2014 and May 2015 and were alternatively assigned for each procedure to either the COBE Spectra or the Spectra Optia cell separator. Patients characteristics and procedure/product parameters were analyzed. RESULTS: Two hundred procedures (100 per device) were included. The Spectra Optia system showed higher total nucleated cells and MNC collection efficiencies (18.6(10.2-29.7) vs 7.9(4.1-14.8)% and 43.6(20.3-59.5) vs 23.3(11.4-37.1)%, P < .001) and monocyte and lymphocyte collection efficiencies (55.2(17.7-83.2) vs 22.8(9-38.9)% and 38.3(26.7-53.4) vs 22.2(9-38.9)%, respectively, P < .001). Absolute platelet loss (PL) and PL per liter of blood processed were significantly lower in the Spectra Optia group (22.9(18.3-28.1) vs 33.6(26.5-41.1)%, P < .001 and 3.7(3.1-4.5) vs 4.3(3.5-4.2)%, P = .01, respectively). However, granulocyte contamination was higher (4.5(1.3-36) vs 1.2(0.4-5.7)%, P < .001) and a higher product haematocrit was obtained with the Spectra Optia (1(0.5-1.6) vs 0.3(0.2-0.5)%, P < .001), without an impact on irradiation time. CONCLUSIONS: In our study, Spectra Optia proved to be safe and effective in collecting MNC with high yield and purity for ECP in GvHD.

Impact of Hematopoietic Progenitor Cell Count as an Indicator for Optimal Timing of Peripheral Stem Cell Harvest in Clinical Practice.

For optimizing CD34+ cell collection, appropriately timing peripheral blood stem cell harvest (PBSCH) initiation is crucial. Automatic cell analyzers with the immature myeloid information channel provide hematopoietic progenitor cell (HPC) count, a surrogate marker of CD34+ cells, which can be obtained within a few minutes without requiring monoclonal antibodies. The final decision on PBSCH initiation can be made using the HPC count obtained on the morning of the harvest day. Herein, we evaluated the impact of the HPC count as an indicator for the optimal timing of PBSCH in clinical practice over 9 years. One hundred and eighteen aphereses from 72 cases had a definite number of CD34+ cells/kg in the PBSC yield. A correlation was found between the HPC count in the PB and the CD34+ cell count (R = 0.563, p ＜ 0.001), whereas no correlation existed between the white blood cell and CD34+ cell counts (R = 0.0418, p = 0.65). We defined ＞ 2.0 × 106/kg of CD34+ cells in a single apheresis as good mobilization. Multivariate analysis demonstrated that an HPC count of ＞ 21/µL, myeloblast count of ＞ 12/µL, and age at PBSCH of ＜ 50 years were independently associated with good mobilization (p = 0.001, p ＜ 0.001, and p = 0.005, respectively). Our findings suggest that the HPC count is a good indicator for the optimal timing of PBSCH.

Factors influencing platelet clumping during peripheral blood hematopoietic stem cell collection.

BACKGROUND: Platelet clumping is a common occurrence during peripheral blood hematopoietic stem cell (HSC) collection using the Spectra Optia mononuclear cell (MNC) protocol. If clumping persists, it may prevent continuation of the collection and interfere with proper MNC separation. This study is the first to report the incidence of clumping, identify precollection factors associated with platelet clumping, and describe the degree to which platelet clumping interferes with HSC product yield. STUDY DESIGN AND METHODS: In total, 258 HSC collections performed on 116 patients using the Optia MNC protocol were reviewed. Collections utilized heparin in anticoagulant citrate dextrose to facilitate large-volume leukapheresis. Linear and logistic regression models were utilized to determine which precollection factors were predictive of platelet clumping and whether clumping was associated with product yield or collection efficiency. RESULTS: Platelet clumping was observed in 63% of collections. Multivariable analysis revealed that a lower white blood cell count was an independent predictor of clumping occurrence. Chemotherapy mobilization and a lower peripheral blood CD34+ cell count were predictors of the degree of clumping. Procedures with clumping had higher collection efficiency but lower blood volume processed on average, resulting in no difference in collection yields. Citrate toxicity did not correlate with clumping. CONCLUSION: Although platelet clumping is a common technical problem seen during HSC collection, the total CD34+ cell-collection yields were not affected by clumping. WBC count, mobilization approach, and peripheral blood CD34+ cell count can help predict clumping and potentially drive interventions to proactively manage clumping.

Autologous lymphapheresis for the production of chimeric antigen receptor T cells.

BACKGROUND: The first step in manufacturing chimeric antigen receptor (CAR) T cells is to collect autologous CD3+ lymphocytes by apheresis. Patients, however, often have leukopenia or have other disease-related complications. We evaluated the feasibility of collecting adequate numbers of CD3+ cells, risk factors for inadequate collections, and the rate of adverse events. STUDY DESIGN AND METHODS: Apheresis lymphocyte collections from patients participating in three CAR T-cell clinical trials were reviewed. Collections were performed on the COBE Spectra by experienced nurses, with the goal of obtaining a minimum of 0.6 × 109 and a target of 2 × 109 CD3+ cells. Preapheresis peripheral blood counts, apheresis parameters, and product cell counts were analyzed. RESULTS: Of the 71 collections, 69 (97%) achieved the minimum and 55 (77%) achieved the target. Before apheresis, the 16 patients with yields below the target had significantly lower proportions and absolute numbers of circulating lymphocytes and CD3+ lymphocytes and higher proportions of circulating blasts and NK cells than those who achieved the target (470 × 106 lymphocytes/L vs. 1340 × 106 lymphocytes/L, p = 0.008; 349 × 106 CD3+ cells/L vs. 914 × 106 CD3+ cells/L, p = 0.001; 17.6% blasts vs. 4.55% blasts, p = 0.029). Enrichment of blasts in the product compared to the peripheral blood occurred in four patients, including the two patients whose collections did not yield the minimum number of CD3+ cells. Apheresis complications occurred in 11 patients (15%) and, with one exception, were easily managed in the apheresis clinic. CONCLUSIONS: In most patients undergoing CAR T-cell therapy, leukapheresis is well tolerated, and adequate numbers of CD3+ lymphocytes are collected.

Stem Cell Harvesting after Bortezomib-Based Reinduction for Myeloma Relapsing after Autologous Transplantation: Results from the British Society of Blood and Marrow Transplantation/United Kingdom Myeloma Forum Myeloma X (Intensive) Trial.

The phase III British Society of Blood and Marrow Transplantation/United Kingdom Myeloma Forum Myeloma X trial (MMX) demonstrated prospectively, for the first time, superiority of salvage autologous stem cell transplantation over chemotherapy maintenance for multiple myeloma (MM) in first relapse after previous ASCT. However, many patients have stored insufficient stem cells (PBSC) for second ASCT and robust evidence for remobilization after first ASCT is lacking. We report the feasibility, safety, and efficacy of remobilization after bortezomib-doxorubicin-dexamethasone reinduction in MMX and outcomes of second ASCT with these cells. One hundred ten patients underwent ≥1 remobilization with 32 and 4, undergoing second and third attempts, respectively. Toxicities of remobilization were similar to those seen in first-line mobilization. After all attempts, 52% of those with insufficient previously stored PBSC had harvested a sufficient quantity to proceed to second ASCT. Median PBSC doses infused, neutrophil engraftment, and time to discharge after second ASCT were similar regardless of stem cell source, as were the toxicities of second ASCT. No significant differences between PBSC sources were noted in depth of response to ASCT or time to progression. Harvesting after bortezomib-doxorubicin-dexamethasone reinduction for MM at first relapse is safe and feasible and yields a reliable cell product for second ASCT. The study is registered with ClinicalTrials.gov (NCT00747877) and EudraCT (2006-005890-24).

Immunologic Autograft Engineering and Survival in Non-Hodgkin Lymphoma.

Retrospective studies have reported that the collected and infused autograft absolute lymphocyte count (A-ALC) affects clinical outcomes after autologous peripheral hematopoietic stem cell transplantation (APHSCT). We hypothesized that manipulation of the apheresis machine to target a higher A-ALC dose would translate into prolonged progression-free survival (PFS) in patients with non-Hodgkin lymphoma (NHL) undergoing APHSCT. Between December 2007 and October 2010, we performed a double-blind, phase III, randomized study randomly assigning 122 patients with NHL to undergo collection with the Fenwal Amicus Apheresis system with our standard settings (mononuclear cells offset of 1.5 and RBC offset of 5.0) or at modified settings (mononuclear cells offset of 1.5 and RBC of 6.0). The primary endpoint was PFS. Neither PFS (hazard ratio [HR] of modified to standard, 1.13; 95% confidence interval [CI], .62 to 2.08; P = .70) nor overall survival (OS) (HR modified to standard, .85; 95% CI, .39 to 1.86; P = .68) were found to differ by collection method. Collection of A-ALC between both methods was similar. Both PFS (P = .0025; HR, 2.77; 95% CI, 1.39 to 5.52) and OS (P = .004; HR, 3.38; 95% CI, 1.27 to 9.01) were inferior in patients infused with an A-ALC < .5 × 10(9) lymphocytes/kg compared with patients infused with an A-ALC ≥ .5 × 10(9) lymphocytes/kg, regardless of the method of collection. We did not detect significant differences in clinical outcomes or in the A-ALC collection between the modified and the standard Fenwal Amicus settings; however, despite physician discretion on primary number of collections and range of cells infused, higher A-ALC infused dose were associated with better survival after APHSCT.

Challenges for CTC-based liquid biopsies: low CTC frequency and diagnostic leukapheresis as a potential solution.

Circulating tumor cells (CTCs) are very attractive surrogate markers for systemic cancer. Currently, major efforts are being made to use these rare cells in the sense of a liquid biopsy to gain molecular information for rational therapeutic decision-making. The advancements in molecular analyses of CTCs down to the single-cell level have been significant in recent years and some applications are ready to be used in clinical studies. As discussed in this review, a major challenge for translating such molecular CTC-based assays into the clinic is the extremely low frequency of CTCs and the associated problems of their reliable detection and isolation. A potential solution to overcome the low CTC frequency is the recently introduced diagnostic leukapheresis that permits screening of liters of blood. Discussed here are the challenges as well as the current efforts implementing this method into clinical workflows to realize more reliable liquid biopsies.

Comparison of two leukocytapheresis protocols in a case of idiopathic hypereosinophilic syndrome.

BACKGROUND: Hypereosinophilic syndrome (HEOS) is rare, and the efficacy of leukocytapheresis in this context is unclear. We here report the successful treatment of a patient with idiopathic HEOS with four leukocytapheresis procedures using two protocols. CASE: A 4-year-old female presented with cardiac and respiratory dysfunction, and WBC of 225 K/µL with 96% eosinophils. Leukocytapheresis was started after initiation of methylprednisolone and hydroxyurea. She received two leukocytapheresis with polymorphonuclear cell (PMN) protocol, followed by initiation of imatinib therapy, then two leukocytapheresis with mononuclear cell (MNC) protocol. After the fourth leukocytapheresis, her WBC decreased to 69 K/µL with 82% eosinophils. She was discharged on hospital day 21 under stable condition with WBC of 22 K/µL with 86% eosinophils. WBC count and eosinophil percentage continued to decrease, and were 6.4 K/µL and 52% by 2 weeks and 3.9 K/µL and 4.9% by 3 months after discharge, respectively. FINDINGS: WBC and absolute eosinophil (aEO) counts decreased by an average of 29.0 and 30.4% per leukocytapheresis, respectively. Normalized to estimated blood volume, procedures with PMN and MNC protocols changed, on average, WBC by -10.7 and -12.1%, aEO by -10.4 and -13.4%, platelet by -8.1 and -19.2%, and fluid balance by -129 and -47 mL, respectively. CONCLUSION: Leukocytapheresis was effective in decreasing WBC and aEO counts in HEOS, with PMN and MNC protocols achieving similar reductions. However, PMN protocol resulted in greater negative fluid balance and MNC protocol resulted in greater platelet loss. J. Clin. Apheresis 31:481-489, 2016. © 2015 Wiley Periodicals, Inc.

Buffy coat volume reduction for optimization of leucapheresis harvests produced by the autoMNC program.

BACKGROUND AND OBJECTIVES: Buffy coat (BC) volume reduction was evaluated in leucapheresis (LA) harvests due to the target monocyte yield and the red blood cell (RBC) content. A packed erythrocyte volume (PEV) of 7.5 ml should not be exceeded to avoid RBC debulking with loss of leucocytes (WBCs) and the monocyte fraction during monocyte counterflow elutriation, a next step of monocyte enrichment prior to cell culture. MATERIALS AND METHODS: Two hundred and fifty-three 5-l leucaphereses (autoMNC program) performed in 102 healthy blood donors (24 female and 78 male donors) were retrospectively analysed. Different categories of BC volumes were compared due to the quality of the LA products measured by blood counts and flow cytometry. RESULTS: Collection of maximum BC volume of 10 ml and more each collection cycle (product volume: 169 ± 21 ml) resulted in 1.58 ± 0·41 × 10e9 CD14(+) monocytes and high volume of packed erythrocyte (18.4 ± 8.8 ml). Low BC volume collection below 6 ml each collection cycle produced only 1.07 ± 0.40 × 10e9 CD14(+) monocytes but reduced PEV significantly by 64% (6.7 ± 4.1 ml). CONCLUSION: By reduction of the BC volume, the PEV in LA products could be reduced, which is a precondition for counterflow elutriation of monocytes. A BC volume between 7 and 8 ml per collection cycle should be adjusted to reduce PEV to 7.5 ml without relevant monocyte loss.

Leukopak PBMC sample processing for preparing quality control material to support proficiency testing programs.

External proficiency testing programs designed to evaluate the performance of end-point laboratories involved in vaccine and therapeutic clinical trials form an important part of clinical trial quality assurance. Good clinical laboratory practice (GCLP) guidelines recommend both assay validation and proficiency testing for assays being used in clinical trials, and such testing is facilitated by the availability of large numbers of well-characterized test samples. These samples can be distributed to laboratories participating in these programs and allow monitoring of laboratory performance over time and among participating sites when results are obtained with samples derived from a large master set. The leukapheresis procedure provides an ideal way to collect samples from participants that can meet the required number of cells to support these activities. The collection and processing of leukapheresis samples require tight coordination between the clinical and laboratory teams to collect, process, and cryopreserve large number of samples within the established ideal time of ≤8 hours. Here, we describe our experience with a leukapheresis cryopreseration program that has been able to preserve the functionality of cellular subsets and that provides the sample numbers necessary to run an external proficiency testing program.

Establishment and maintenance of a PBMC repository for functional cellular studies in support of clinical vaccine trials.

A large repository of cryopreserved peripheral blood mononuclear cells (PBMCs) samples was created to provide laboratories testing the specimens from human immunodeficiency virus-1 (HIV-1) vaccine clinical trials the material for assay development, optimization, and validation. One hundred thirty-one PBMC samples were collected using leukapheresis procedure between 2007 and 2013 by the Comprehensive T cell Vaccine Immune Monitoring Consortium core repository. The donors included 83 human immunodeficiency virus-1 (HIV-1) seronegative and 32 HIV-1 seropositive subjects. The samples were extensively characterized for the ability of T cell subsets to respond to recall viral antigens including cytomegalovirus, Epstein-Barr virus, influenza virus, and HIV-1 using Interferon-gamma (IFN-γ) enzyme linked immunospot (ELISpot) and IFN-γ/interleukin 2 (IL-2) intracellular cytokine staining (ICS) assays. A subset of samples was evaluated over time to determine the integrity of the cryopreserved samples in relation to recovery, viability, and functionality. The principal results of our study demonstrate that viable and functional cells were consistently recovered from the cryopreserved samples. Therefore, we determined that this repository of large size cryopreserved cellular samples constitutes a unique resource for laboratories that are involved in optimization and validation of assays to evaluate T, B, and NK cellular functions in the context of clinical trials.

Development of model for analysing respective collections of intended hematopoietic stem cells and harvests of unintended mature cells in apheresis for autologous hematopoietic stem cell collection.

Hematopoietic stem cells (HSCs) required to perform peripheral hematopoietic autologous stem cell transplantation (APBSCT) can be collected by processing several blood volumes (BVs) in leukapheresis sessions. However, this may cause granulocyte harvest in graft and decrease in patient's platelet blood level. Both consequences may induce disturbances in patient. One apheresis team's current purpose is to improve HSC collection by increasing HSC collection and prevent increase in granulocyte and platelet harvests. Before improving HSC collection it seemed important to know more about the way to harvest these types of cells. The purpose of our study was to develop a simple model for analysing respective collections of intended CD34+ cells among HSC (designated here as HSC) and harvests of unintended platelets or granulocytes among mature cells (designated here as mature cells) considering the number of BVs processed and factors likely to influence cell collection or harvest. For this, we processed 1, 2 and 3 BVs in 59 leukapheresis sessions and analysed corresponding collections and harvests with a referent device (COBE Spectra). First we analysed the amounts of HSC collected and mature cells harvested and second the evolution of the respective shares of HSC and mature cells collected or harvested throughout the BV processes. HSC collections and mature cell harvests increased globally (p<0.0001) and their respective shares remained stable throughout the BV processes (p non-significant). We analysed the role of intrinsic (patient's features) and extrinsic (features before starting leukapheresis sessions) factors in collections and harvests, which showed that only pre-leukapheresis blood levels (CD34+cells and platelets) influenced both cell collections and harvests (CD34+cells and platelets) (p<0.001) and shares of HSC collections and mature unintended cells harvests (p<0.001) throughout the BV processes. Altogether, our results suggested that the main factors likely to influence intended HSC collections or unintended mature cell harvests were pre-leukapheresis blood cell levels. Our model was meant to assist apheresis teams in analysing shares of HSC collected and mature cells harvested with new devices or with new types of HSC mobilization.

First comparative evaluation of a new leukapheresis technology in non-cytokine-stimulated donors.

BACKGROUND AND OBJECTIVES: Leukapheresis is an important source for mononuclear cells (MNCs) used in adoptive immunotherapies. Differences in the apheresis technology concerning physical conditions during cell separation and the optical detection system can affect the product's cellular content. MATERIALS AND METHODS: In a paired analysis, twenty healthy non-cytokine-stimulated donors underwent MNC collection at the Spectra Optia (Terumo BCT, Lakewood, CO, USA) and the COM.TEC (Fresenius Kabi, Bad Homburg, Germany) device. In twelve donors, apheresis was additionally performed with the Amicus (Fenwal Inc., Lake Zurich, IL, USA). Donor response to leukapheresis and product composition was compared. RESULTS: Mean yields of CD14+ (CD3+) cells were 1·64±0·70x10(9) (2·36±0·96×10(9)) in the Spectra Optia, 1·45±0·50×10(9) (3·03±1·04×10(9)) in the COM.TEC and 1·20±0·37×10(9) (2·80±1·00×10(9)) in the Amicus products, respectively. The Spectra Optia collected significantly more CD14+ monocytes than the Amicus and significantly less CD3+ T cells than the COM.TEC (P=0·002 and P=0·021). Apheresis products of the Spectra Optia showed the significantly lowest red blood cell yields while the Amicus generated products with the significantly lowest platelet contents. CONCLUSIONS: Leukaphereses with the three devices resulted in almost equal total MNC yields. MNC products of the Spectra Optia and the Amicus could be used in preference for the monocyte enrichment by the Elutra system and the leukapheresis procedures could be also favourably applied in patients with low platelet counts. The COM.TEC is more efficient in monocyte and T-cell collection with the disadvantage of high residual non-target cell content in the products.

Hyperleukocytosis and leukocytapheresis in acute leukaemias: experience from a single centre and review of the literature of leukocytapheresis in acute myeloid leukaemia.

BACKGROUND: Hyperleukocytosis is usually defined as leukocyte count >100 × 10(9) L(-1) and can be seen in newly diagnosed leukaemias. Hyperleukocytic leukaemia is associated with a risk of organ failure and early death secondary to leukostasis. Mechanical removal of leukocytes by the apheresis technique, leukocytapheresis, is a therapeutic option in these patients. METHODS: During a 16-year period, 16 patients were treated with leukocytapheresis (35 apheresis procedures) for hyperleukocytosis/leukostasis. We present our experience, and in addition we review previous studies of hyperleukocytosis/leukocytapheresis in patients with acute myeloid leukaemia (AML). RESULTS: We used a highly standardised approach for leukocytapheresis in leukaemia patients with hyperleukocytosis. The average leukocytapheresis number for each patient was 2·2 (range 1-6). Median leukocyte count before apheresis was 309 × 10(9) L(-1) (range 104-935); the mean leukocyte count reduction was 71%, corresponding to a mean absolute reduction of 219 × 10(9) L(-1). No serious side effects were seen during or immediately after apheresis. CONCLUSIONS: The data suggest that our standardised technique for leukocytapheresis effectively reduced the peripheral blood leukaemia cell counts. Previous studies in AML also support the conclusion that this is a safe and effective procedure for the treatment of a potentially life-threatening complication, but apheresis should always be combined with early chemotherapy.

Anticoagulation in large-volume leukapheresis: comparison between citrate- versus heparin-based anticoagulation on safety and CD34 (+) cell collection efficiency.

BACKGROUND AIMS: Little is known of the effect of anticoagulation on peripheral blood progenitor cell (PBPC) harvest during large-volume leukapheresis (LVL). Because of the interaction of heparin with stromal cell-derived factor (SDF)-1α, it has been proposed that a heparin-based anticoagulation may result in an increased PBPC collection efficiency compared with standard citrate-based anticoagulation. METHODS: We conducted a prospective randomized trial to address the effect of both anticoagulation regimes on safety, subjective comfort and CD34 (+) collection efficiency in 90 adult patients undergoing standardized LVL. Anticoagulation consisted of either citrate (group C) or a combination of heparin and low-dose citrate (group H). RESULTS: The overall incidence of adverse reactions (AR) during LVL was 17%. AR consisted only of citrate-related AR; no bleeding complications were observed. Determination of parameters of the acid-base balance revealed a higher frequency of metabolic alkalosis in group C. Analysis of serum SDF-1α revealed no differences in SDF-1α plasma levels. There were no differences in the CD34 (+) cell collection efficiency, resulting in the harvest of equal CD34 (+) cell yields independent of the anticoagulation used. CONCLUSIONS: Our data show no clinical relevant effect of a heparin containing anticoagulation in terms of an increased overall CD34 (+) cell collection during LVL, although this regime shows some benefits in terms of the incidence and subjective tolerance towards AR. Based on our results the decision between a citrate- and heparin-substituted anticoagulation for LVL should be driven by patient-related factors, and should concern potential contraindications of both methods.